How to reverse string and array in php

In PHP, you can use the strrev() and array_reverse() functions to achieve string reversal and array reversal. strrev() is used to reverse a string, the syntax is "strrev($string)". array_reverse() is used to reverse an array, the syntax is "array_reverse($array,$preserve)"; the parameter "$preserve" can be omitted, the default value is "false", if the value is set to TRUE, the numeric keys will be retained.

The operating environment of this tutorial: windows7 system, PHP8.1 version, DELL G3 computer

php has two built-in functions. Implement string reversal and array reversal

• ##strrev()

• array_reverse()

strrev() function can reverse string

strrev($string) Function to reverse string$string .

• Return value: Returns the reversed string.

Example:

<?php
header("Content-type:text/html;charset=utf-8");
$str="Hello World!";
echo "原字符串：".$str."<br>";
echo "反转字符串：".strrev($str);
?>

array_reverse() can achieve array reversal

The array_reverse() function can reverse an array, returning the array in reverse order. Syntax format:

array_reverse($array,$preserve)

##Parameter$array$preserveIf set to TRUE, numeric keys will be preserved. Non-numeric keys are not affected by this setting and will always be retained. ##Example: output original array, reverse Array, reverse array retaining the original array key name

<?php
header("Content-type:text/html;charset=utf-8");
$a=array("Volvo","XC90",array("BMW","Toyota"));
$reverse=array_reverse($a);
$preserve=array_reverse($a,true);
var_dump($a);
var_dump($reverse);
var_dump($preserve);
?>

Description
Required. Specifies an array.
Optional. Specifies whether to retain the original array key names.	Possible values: true false

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